Users of desktop telephone terminals often find it convenient to access a frequently dialled number by touching relatively few buttons (or keys) on the keypad, a technique known in the art as speed calling. In situations where multiple telephone lines are available at a single terminal, it is also considered efficient to be able to access a particular line by depressing a single key corresponding to the desired line. Furthermore, with an ever increasing number of features available to users of desktop terminals, such as conference call, call park, call forward and automatic redial, users find it beneficial when these features are available at the touch of a button.
Such issues have been at least partially considered by manufacturers of modern desktop terminals, having given rise to a variety of designs of attachable (or add-on) modules attempting to satisfy today's user. A simple solution involves so-called keycap labelling, whereby a certain number of buttons on the module are reserved for speed calling, multiple lines and distinct features. At the time of manufacture of the add-on module, the actual telephony function of each of the reserved buttons is imprinted on the button itself.
Although it permits easy access to several functions in addition to those already available on the terminal, this implementation suffers from being inflexible and inefficient. For example, the mapping which associates each "speed call" button with a particular person's number must be recorded by the user of the module, either in memory or elsewhere. Moreover, it is generally impossible to increase the number of functions beyond the number of keys available on the module, or to re-map particular buttons to specific functions.
Another design, known in the art as paper strip labelling, permits the user to associate personalized information with each button by simply writing this information on a piece of paper and inserting it in a pocket on the button proper. More sophisticated attachable modules employing this design also allow the user of a module to assign each available key to any available function, and to reconfigure this mapping at will.
However, it is still a problem to access a number of telephony functions in excess of the number of keys on the module. Furthermore, hidden costs await the user or telephone provider as new labels of an adequate size must be printed upon modification of features, line numbers or the names of people on the speed call list. Clearly, any gain in flexibility is more than offset by additional maintenance requirements.
It would therefore be desirable to increase the capability and flexibility of a desktop terminal through the provision of a cost-efficient and maintenance-free display-based attachable module offering one-button access to various telephony functions.